New research confirms rise in tick threat
The appearance of Lyme disease on the Western Isles confirms it has the potential to emerge in a wider range of habitats than previously thought, suggests new research by the Universities of Liverpool and Glasgow.
The new study, published in Emerging Infectious Diseases, found that open, treeless habitats can support similar densities of infected ticks as woodland in the UK, challenging established knowledge of which habitats present the most disease risk.
Lyme disease – an infection contracted from the bite of an infected tick – is already growing in incidence in people in the UK and large parts of Europe and North America.
It is usually associated with forested habitats but over the past decade has, somewhat surprisingly, emerged on treeless islands in the Western Isles.
Researchers from the two universities, in collaboration with NHS Western Isles and NatureScot, examined the different human and environmental factors which could have contributed to the rise of Lyme disease in the Western Isles.
Superficially, the habitats and the climate of these islands look very similar, yet the incidence of Lyme disease on some islands is 40 times higher than the national average for Scotland, while other nearby islands are relatively less affected.
On islands with a high incidence of Lyme disease, the researchers found that open habitats, including grassland and domestic gardens, had similar tick density and prevalence of infected ticks as forested mainland sites in Scotland.
Co-lead researcher Dr Roman Biek from the University of Glasgow said: ‘This is a striking finding and suggests that microclimatic conditions in these open habitats, possibly driven by the milder oceanic climate on the Western Isles, can be as conducive to tick survival as conditions in woodlands.’
The survey results also found that residents on islands with a high incidence of Lyme disease were more likely to be bitten by ticks, with most people being bitten close to their home or in their gardens.
Residents also reported increasing problems with ticks, with many suggesting increasing numbers of deer, and deer coming closer to people’s homes, as a potential driver.
Co-lead researcher Caroline Millins from the University of Liverpool, said when she and her colleagues visited the islands and attended community meetings, there were significant concerns raised by residents about frequent tick bites in their gardens.
NatureScot Outer Hebrides Operations Manager Johanne Ferguson added: ‘This important piece of research confirms what many in the Uist community have been reporting for some time – that infected ticks are being found much closer to home.
‘The Lyme Disease Research project is carrying out ongoing research into this, which will inform NatureScot’s work with the Uist community, the Uist Deer Management Group and others to find ways to reduce the tick burden in and around villages.’
Isabell MacInnes, public health nurse specialist with NHS Western Isles, said: ‘We are aware of the increasing numbers of cases of Lyme disease being reported in people living in the Western Isles, and we welcome the evidence provided through this research, which we will use to guide future public health actions.’